Tuesday, March 27, 2007

Plastics

There's an old joke that if you were reincarnated, you might want to come back as a polystyrene foam cup.

Why? Because they last forever. Ba-dum-bum.

Despite being made 95 percent of air, polystyrene foam's manufactured immortality has posed a problem for recycling efforts. More than 3 million tons of the durable material is produced every year in the United States, according to the U.S. Environmental Protection Agency. Very little of it is recycled.

Help may come from bacteria that have been found to eat polystyrene foam and turn it into useable plastic. This is the stuff recycling dreams are made of: Yesterday's cup could become tomorrow's plastic spoon.

....converted it into biodegradable plastic known as PHA (polyhydroxyalkanoates).

PHA can be used to make plastic forks and packaging film. It is resistant to heat, grease and oil. It also lasts a long time. But unlike polystyrene foam, PHA biodegrades in soil and water.Which is of interest to the cruise ship industry and the US Navy:

A biodegradable plastic that dissolves into nontoxic components in seawater could make it environmentally safe to ditch "disposable" forks, spoons, wraps and other such waste overboard from ships to free up valuable space.

....Cruise liners, naval warships and other vessels generate huge volumes of plastic trash, such as stretch wrap for large cargo items, food containers and eating utensils. This junk often remains onboard for long spans of time until ships make port. Simply dumping such junk overboard is hazardous because conventional plastics can take years to break down and may result in toxic byproducts.

When exposed to seawater, the new plastics can dissolve in as few as 20 days.